What term describes an identification key that divides organisms progressively into smaller groups?

The term that describes an identification key that divides organisms progressively into smaller groups is a dichotomous key. A dichotomous key functions as a tool that aids in the identification of organisms by presenting a series of choices that lead to the correct name of a species. Typically, these choices are based on observable physical characteristics or traits. The key begins with broad categories and gradually narrows down the options, allowing users to systematically eliminate possibilities until they arrive at a specific organism.

In this structure, each step presents two contrasting statements, from which the user must choose the one that fits the organism being identified. This methodical approach helps in organizing biological diversity and enhances identification accuracy, making it an essential tool in taxonomy and biology studies.